arm64: dts: sdm845: Fix xo_board clock name and speed

The RPMh clock driver assumes that the xo_board clock is named "xo_board", not "xo-board". Add a "clock-output-names" property to the device tree to get the right name.

Also add the proper speed for the xo-clock as 38400000. This is internally divided in RPMh clock driver to get "bi_tcxo" at 19200000.

After this change the clock tree in /sys/kernel/debug/clk/clk_summary looks much better.

NOTES:
- Technically you could argue that this clock could belong in board .dts files, not in the SoC one. However at the moment it's believed that 100% of sdm845 boards will have an external clock at 38.4. It can always be moved later if necessary.
- We could rename the "xo-board" device tree node to "xo_board" to achieve the same effect as this patch. Presumably device-tree folks would rather keep node names using dashes though.
- We could change the RPMh clock driver to use a dash to achieve the same effect as this patch, but all other clocks in the clock tree use underscores. It seems silly to change just this one.

---

 arch/arm64/boot/dts/qcom/sdm845.dtsi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 486ace9a9e8b..4945f8cccd6c 100644
@@ -137,7 +137,8 @@
 		xo_board: xo-board {
 			compatible = "fixed-clock";
 			#clock-cells = <0>;
-			clock-frequency = <19200000>;
+			clock-frequency = <38400000>;
+			clock-output-names = "xo_board";
 		};
 
 		sleep_clk: sleep-clk {

2.17.0.441.gb46fe60e1d-goog